For the preparation of the diamond preforms, syntheticdiamond powders (VDiamant Ltd., Seddiner See, Germany)with different average grain sizes of 5, 10, 20, 50, and100 lm were used as starting powders. The content ofmetallic impurities of the used diamond powders were lessthan 0.05 wt%. For shaping of the preforms two differentorganic binders novolac resin and cellulose binder wereused.